Mustang Drifting Checklist:
[ ] Posi/lsd Diff (GT-Cobra or aftermarket)
[ ] Suspension (springs/struts/swaybars or full coil-overs)
[ ] Angle... as much as you can get. (wheel spacers and remove the urethane rack limiters inside the boots - then heavy steering modifications)
[ ] Power
In that order (unless its a v6 then you'll need a little more power in the begining)
Other than that, Welcome and enjoy the community!